2,419 research outputs found
D-branes in group manifolds and flux stabilization
We consider D-branes in group manifolds, from the point of view of open
strings and using the Born-Infeld action on the brane worldvolume. D-branes
correspond to certain integral (twined) conjugacy classes. We explain the
integrality condition on the conjugacy classes in both approaches. In the
Born-Infeld description, the D-brane worldvolume is stabilized against
shrinking by a subtle interplay of quantized U(1) fluxes and the non-triviality
of the B-field.Comment: 6 pages. Invited talk at the 9th Marcel Grossmann meeting, Rome, July
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Spontaneous breaking of axial symmetry for Schroedinger's equation in the presence of a magnetic field
For appropriate parameters, the ground state for the Schroedinger and Ampere
coupled equations in a cylindric domain does not have axial symmetry.Comment: 2 page
The action of outer automorphisms on bundles of chiral blocks
On the bundles of WZW chiral blocks over the moduli space of a punctured
rational curve we construct isomorphisms that implement the action of outer
automorphisms of the underlying affine Lie algebra. These bundle-isomorphisms
respect the Knizhnik-Zamolodchikov connection and have finite order. When all
primary fields are fixed points, the isomorphisms are endomorphisms; in this
case, the bundle of chiral blocks is typically a reducible vector bundle. A
conjecture for the trace of such endomorphisms is presented; the proposed
relation generalizes the Verlinde formula. Our results have applications to
conformal field theories based on non-simply connected groups and to the
classification of boundary conditions in such theories.Comment: 46 pages, LaTeX2e. Final version (Commun.Math.Phys., in press). We
have implemented the fact that the group of automorphisms in general acts
only projectively on the chiral blocks and corrected some typo
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